The present invention relates in general to an antenna device, for receiving and transmitting RF signals with .a sliding connector means, and more specifically to an antenna device for receiving and transmitting RF signals, which is electrically coupled to radio circuitry through a sliding connector during its extension and retraction.
Some of the driving forces of the mobile communication industry today are availability and size. A user of a hand-held mobile communication device requires to be reached wherever his location may be. This puts requirements on the operator to have good coverage of their mobile network, but for large unpopulated or scarcely populated areas, this is not possible with any reasonable economy. One solution for a user who frequently travels to unpopulated locations is to instead use a satellite communication telephone.
Such a user will still have requirements on the size of his satellite communication device, as he undoubtedly will compare his ordinary cellular communication device with his satellite communication device. Since the distance to orbiting or stationary satellites is so great, satellite antennas need to be able to handle very weak signals. The antennas used will thus generally be larger and require less obstacles compared to antennas for cellular communication devices, and will consequently take a considerable amount of the space of a satellite communication device. The need for reducing the size of the antennas for satellite communication devices is thus large and anyone being able to reduce the size for such an antenna will have a considerable competitive advantage.
The somewhat larger antenna unit in a satellite communication device has posed some problems. In one set of prior art antennas the antenna unit can be rotated around an axis so as to fold the antenna unit along one side of the satellite communication device when not in talk position. Thereby, the space taken by the terminal device is considerably less when in a standby mode. One problem, which occurs with this solution, is that the antenna is badly suited to receive paging signals from the satellite in the standby mode. This can be remedied by introducing an extra paging antenna on the top of the satellite communication device specifically designed for receiving signaling in the standby mode. This, however generates a new problem namely with how to switch between the different antennas in dependence of the operating mode.
Another solution requires the satellite device to have a specific position during standby, such as upside down. The U.S. patent application Ser. No. 5,628,057 discloses a satellite communication device with an antenna unit connected thereto at a pivot point.
The object of the present invention is thus to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable in both extended and retracted position.
Another object of the present invention is to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable during extension and retraction.
The problems described above, how to achieve a reliable and efficient connection between circuitry in a radio communication device and an extendable and retractable antenna device, which is operable in both extended and retracted position as well as during extension and retraction, is solved by providing an antenna device with radiating means, movable between a extended and a retracted position. Said antenna device having a feeding arrangement comprising at least a first connection member electrically coupled to and movable with said radiating means. Said feeding arrangement further comprises at least a second connection member arranged for being electrically coupled to said first circuitry and fixedly mounted on a support unit. Moreover, said first connection member being electrically coupled to said second connection member in all positions between and including said extended and retracted positions.
In more detail the objects of the present invention are obtained, according to a first embodiment, by providing an antenna device according to the above, wherein said first connection member comprises a multitude of resilient conductive members. Said second connection member comprising a multitude of elongated conductive strips arranged on one side of a dielectric medium and with a ground plane arranged on an opposite side of said dielectric medium. Each resilient conductive member of said multitude of conductive members being arranged to exert a force against a corresponding elongated conductive strip so as to enable electrical coupling between said conductive member and said conductive strip. Each resilient conductive member being arranged to slide along said elongated conductive strip when said radiating means moves between said first and second positions.
According to another embodiment, the objects of the present invention are obtained by providing an antenna device according to the above, wherein said antenna device further comprises a switch. Said switch being arranged for disconnecting said second connection member and connecting said first circuitry to said radiating means when said radiating means is in said second position.
According to another embodiment, the objects of the present invention are obtained by providing an antenna device according to the above, wherein at least one of said elongated conductive strips having irregular shaped edges. Said irregular shaped edges being adjusted so that the elongated conductive strip having an input impedance, seen from a first point where the resilient conductive member connects to the elongated conductive strip when said radiating element is in extended position, and towards said open end which is very large compared to the input impedance seen from said first points and towards the radiating means. These irregular shaped edges can for instance be obtained by protrusions and/or recesses.
An advantage with the present invention is that a reliable connection between the circuitry in a radio communication device and an extendable radiating means is obtained in extended and retracted position as well as during extension and retraction.
Another advantage with the present invention is that the shortest possible electrical transmission distance is kept between the radiating element and the radio circuitry in both extended and retracted position.
An advantage, according to one embodiment of the invention, is that several independent, electrically separate connections between circuitry in a radio communication device and an extendable radiating means can be obtained easily and reliably.
An advantage, according to one embodiment of the invention, is that power and control signals can easily and reliably be fed to circuitry located on the radiating means.
An advantage, according to one embodiment of the invention, is that transmitted and received signals can be conducted on separate lines between the radiating means and the circuitry in the radio communication device.
An advantage, according to one embodiment of the invention, is that signals to different radiating elements, arranged for receiving and transmitting RF signals in different systems can be conducted on separate lines between the radiating means and the circuitry in the radio communication device.
Another advantage, according to one embodiment of the invention, is that said elongated conductive strip may have irregular shaped edges, such as protrusions or recesses, so that the elongated strip is to be regarded as an open circuit when said radiating means is in its extended position.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.